Addison's disease in dogs

Written by AniMed.org
Reviewed by Kristin Westafer, DVM

Addison's disease, also known as hypoadrenocorticism or adrenal insufficiency, is a very serious condition that requires immediate medical attention. Addison's disease causes a variety of symptoms and can be fatal if not properly treated or left untreated for a short period of time. The disease occurs because of a damage to the two adrenal glands. The adrenal glands are small hormone producing glands that are located above both kidneys.

Addison's disease comes in three different forms: primary, secondary and atypical. Primary Addison's is usually caused by an abnormal response of the immune system that causes the body to attack its own tissue. As a result of this autoimmune response, the adrenal glands are damaged. A tumor of the adrenal gland can also cause primary Addison's disease. Secondary Addison's disease is very rare and is the result of a lack of adrenocorticotropic hormone, also called ACTH, which is actually produced in the brain. Atypical Addison's disease can also be caused by an immune response. Addison's disease can sometimes be triggered by abruptly halting oral steroid treatments instead of tapering the dose down slowly. Addison's disease is not common, but when diagnosed, it is often in purebred dogs. The Bearded Collie, Portuguese Water Dog, and Standard Poodle are three breeds most often affected.

Diagnosis

Addison's disease can be difficult to diagnose as it has symptoms that are similar to many other medical conditions; it is often called "the great pretender." Diagnosis is always confirmed by having blood work done.

The ACTH stimulation or response test is the only test that can accurately diagnose Addison's disease. The test requires that a blood sample be drawn, the dog be injected with the ACTH hormone, and then another blood test taken to measure the dog's response to the ACTH. The test is time sensitive so you may have to leave your dog with Veterinarian for a few hours. Normal dogs respond to the ACTH by producing a large amount of a steroid, known as cortisol. Dogs with Addison's disease cannot make their own steroids and they do not respond well or at all to the ACTH.

Measuring electrolyte levels is another way to diagnose Addison's because dogs with this disease often suffer from significant electrolyte imbalances. This method is not as effective as the ACTH test and should not be considered a diagnosis by itself.

Symptoms

Lethargy
Lack of appetite
Diarrhea
Vomiting
Muscle weakness
Shivering
Extreme weakness
Low heart rate
Weight loss
Regurgitation
Inability to rise
Dehydration

Prevention

It has not been discovered yet how to prevent Addison's disease. Researchers are exploring a genetic link to the disease, so dogs suffering from Addison's should not be bred.

To prevent dogs from developing Addison's after receiving a course of corticosteroids (usually prednisone), the drug should be gradually decreased rather than halting the medication abruptly. This gives the body time to begin making its own steroids again after being given steroids by mouth over a period of time.

Treatment

Treatment for Addison's involves use of one or more medications. Veterinarians commonly prescribe Florinef or Percorten-V, which replace one of the hormones lacking in dogs with Addison's. Florinef is a pill that has to be given at home on a daily basis and Percorten-V is an injection that is given under the skin by your veterinarian once a month. Called aldosterone, the main hormone in these treatments maintains normal electrolyte levels in the dog's body. Prednisone is often prescribed as well, to be given on a daily basis and when you suspect your dog will be stressed, because it replaces hormones that are not being produced normally by a dog suffering from Addison's disease.

If your dog's Addison's disease has gone unnoticed or if it has developed very rapidly, your dog may have an "Addisonian crisis." This is a life threatening condition that must be treated immediately by a veterinarian. Without the body's natural steroids, dogs with this condition have extremely low blood pressure, dangerously high levels of potassium, and will ultimately die of shock if left untreated. Your dog will need to be hospitalized for steroids and IV fluids. If caught early enough, dogs in a crisis situation often do very well after treatment.

After treatment

Remember, Addison's disease is a lifelong condition. Once your dog has been diagnosed with this disease, treatment will continue to be necessary for life. Your dog will require monitoring by your veterinarian, to make sure medications are dosed appropriately. If well managed, dogs with Addison's disease can live full, active lives. You will probably be surprised at how much energy your dog has once his Addison's disease is under control!